Harper, who is 5-foot-11, 230 pounds, said he had always planned to play three years of college football.
"I feel prepared for this," Harper said. "I feel my coaches have prepared me to be a hard-nosed professional football player."
"I feel I can run past you or I can run through you," Harper said. "I learned a lot from guys like C.J. and James and I feel good about my Clemson career."
Harper ran for 760 yards and had 10 touchdowns during his junior season.
Joe Schad is a college football reporter for ESPN.com.